Cyst in Armpit Causes Treatments And When to See a DoctorNodule caused by a follicle may be a painful issue which needs adequate treatment. Such form of cyst arises when an ingrown hair grows in into your epidermis, causing swelling and possible infection. Treating a cyst resulting from an hair effectively may help alleviate unease and stop additional problems. In case you are having difficulties with a cyst, seeking professional guidance is advisable to manage it properly and prevent any potential risks associated with self-treatment.